Azo dyes of the pyrazolone series and process of making same



.Patented May 26, 1925 v UNITED STATES PATENT OFFICE.

MELOHIOR BOENIGER, OF BASEL, SWITZERLAND, AS-SIGNOR 'IO SOCIETY CHEMICAL WORKS FORMER/LY SANDOZ, 0F BASEL, SWITZERLAND.

AZO DYES OF THE PYRAZOLONE SERIES AND PROCESS OF MAKING SAME.

Ho Drawing.

. To all whom it may concern:

Be it known that I, MELCHIOR BoENIeEn, a citizen of the Swiss Republic, and resident of Basel, Switzerland, have invented new and useful Azo Dyes of the Pyrazolone Series and Processes of Making Same, of which the following is a full, clear, and exact specification.

The present invention relates to the man ufacture of new and valuable azo dyes of the yrazolone series by combining the 1.2.- 5'- ichloro-3' sulfophenyl 3 methyl-5-pyrazolone corresponding to the constitution -sona with dia'zo compounds.

The new pyrazolone used in this process r derives from the hitherto unknown paradichlorometanilic acid, which can be obtained by sulfonation of paradichlorobenzene and subsequent nitration and reduction. By condensin the corresponding paradichloro pheny ydrazinemetasulfonic acid with ethyl-aceto-acetate the new 1.2'.5'-dichloro 3 sulfophenyl 8 methyl -5-pyrazolone is obtained.

This new pyrazolone can easily be coupled in alkaline solution with various diazocompounds, yielding azo dyes, ,which dye wool from an acid bath in ellow shades, remarkable for the purity of their tints, their excellent equalizing properties and their nearly absolute fastness to light. Compared with the well known corresponding azo dyes of the 1.2.5'-dichloro-4-sulfophenyl-3-methyl-5- yrazolone they dye slightl more greenis in shade, the dyeings being ess sensitive to metals and metal salts especially copper and copper salts. They .form in dry state yellow powders, dissolvin in water and in strong sulfuric acid wit greenish Application filedv February Ewample.

Add to a solution of-323 parts of 1.2. 5- dichloro-3-sulfophenyl -3-methyl-5 pyrazolone and 160 parts of calcinated sodium carbonate in about 1600 parts of water at a temperature not exceeding 10 C. the diazosulfonic acid obtained in the well known manner from 173 parts of orthoanilinesulfonic acid, care being taken that slightly alkaline reaction can be traced until the end. The diazo compound disappears in some minutes; the clear greenish yellow solution thus obtained is heated up to 75 0., acidulated with hydrochloric acid and the dyestufi' is precipitated by addition of common salt; filtered off and dried it forms a greenish yellow powder, which dissolves easily in water with greenish yellow coloration. The new coloring matter dyes wool from an acid bath binin inan alkaline solution a diazo compoun with 1.2.5'-dichloro-3'-suliophenyl- 3-methyl-5-pyrazolone of the fornmla CHg-il 2. As new products of manufacture the azo dyes obtained as herelnbefore described by combining in an alkaline solution a diazo with the air pure blue-red. compound with 1.2.5'dichloro-3sulfo- In Witness whereof I have hereunto signed 10 phenyl-Zi-methyl-5-pyrazolone, being in drymy name this 20th day of January 1925, in state yellow powders, easily soluble in water the presence of two subscribing witnesses.

and in strong sulfuric acid with yellow MELOHIOR BOENIGER. color, their neutral watery solution boiled Witnesses: I with zinc dust being decolorized, the solu- ARMANI) BEARNE,

tion thereby obtained becoming in contact 7 JQsEPI-I RIEKJEN. 

